Navigation instrument



F. A. REECE NAVIGATION INSTRUMENT Jan. E6, i945.

2l SheeS-Sheet l Filed July 29, 1,941

Mlm-Summa YIva-2+.

Q & o m :m.v

Jan. 16, 1945.

F. A. REECE y NAVIGATION INSTRUMENT Filed July 29, 1941 2 Sheets-Sheet 2IH Lrlml .Lann

IAM.

` Patented Jan. 16, 1945 UNITED 'STATES PATENT OFFICE NAVIGATIONINSTRUMENT Franklin A. Reece, Brookline, Mass.

Application July 29, 1941, Serial No. 404,480

(Cl. 23S-61) 8 Claims.

This invention relates to a combined map gauge and computing instrumentadapted especially, although not exclusively, to aerial navigation, andcapable, in conjunction with a suitable map, or, in some instancesindependently thereof, to indicate directly the time required to covergiven distances, or, conversely, the distances covered in, given times,at a given ground speed, as well as affording convenient means fordirectly determining actual ground speed. By setting the instrument forthe estimated or assumed ground speed, a time register or indicatormovable over a distance scale to different positions thereon is causedto indicate the time required (at that ground speed) to cover anydistance determined by its position on the scale, or, conversely, itsposition on the scale will indicate the distance covered in a givenelapsed time registered by the indicator, so that, by applying thedistan-ce scale to a map, the prospective time of arrival at a givenobjective will be shown, and the pilots position at any given time (asshown by a suitable timepiece) can be ldetermined whether the ground isvisible or not. The correctness of the original assumption as to groundspeed (and the consequent initial setting of the instrument for thisfactor) can be checked; and veried or corrected, at an early period inthe ilight (and from time to time thereafter) by observing the time oiarrival over a recognizable landmark whose distance from a startingpoint is known or can be scaled on the map, comparing this with the timeregistered by the time indicator when positioned on the distance scaleto correspond to this distance, and the ground speed setting changed, ifnecessary, to make the time indicator register the actual observed time,whereupon the ground speed will be directly shown by such setting.

The ability to determine actual ground speed quickly and accurately isitself a great advantage, and so is the ability to make frequentlyrepeated checks wthoutusing a great deal of the 'navigator's time forcomputations. There is also the further advantage that the instrumentaids the navigator in dead reckoning (in which a course is estimatedfrom the air speed and the direction and velocity of the wind) bysupplying a check on the speed along the projected path taken.

The invention will be best understood from the following description inconjunction with the accompanying drawings. It is tov be understood thatthe invention is not limited to the details of construction andarrangement of parts illustrated in the drawings, since the invention,as deiined by the claims hereinafter appended, may be otherwise embodiedwithout departure from the spirit and scope thereof.

It is also to be understood that the terms here used are for the purposeof description and not of limitation, and it is not intended to limitthe invention claimed herein beyond the requirements of the prior art.

In said drawings:

Fig. l is a plan view of a device embodying the invention;

Fig. 2 is a side elevation thereof, partly in section;

Fig. 3 is an end View as seen from the right of Fig. 2;

Fig. 4 is a section taken on the line 4-4 of Fig. 2;

Fig. 5 is a development of the time indicator drum;

Fig. 6 is a View similar to that of Fig. l but showing the instrumentset up for a different ground speed;

Fig. 7 is an endview as seen from the right of Fig. 6; and

Fig. 8 is a diagrammatic view illustrating the use of the instrumentl inconnection with a map.

The instrument shown in the drawings comprises a rule body l providedalong one edge with a distance, scale 2 graduated in units of distance,e. g. miles. The scale oi the graduations corresponds to that of the mapin connection with which the instrument is to be used. A circularchannel 3 is formed longitudinally in said rule body I, and extendinglongitudinally through said channel is a (preferably metallic) flexibleguide or controller strip 4 anchored at one end (preferably ashereinafter described) to the rule body at that end of. the channel 3nearest the zero point on the scale 2. The other end of said strip isreceived in a slot 8 in a projection 9 extending coaxially from theinner face of a gear I0 mounted on a. shaft I I journalled in the end ofthe rule body I opposite the zero point on the scale 2. Displacement ofthe shaft II is prevented by a ring I2 in the annular channel I3 of theshaft II. Held in mesh with gear I0 is a pinion I4 mounted on a shaft I5similarly journalled in the lrule body I. Secured to the other end ofthe shaft I5 by a pin I6 is a' speed indicator dial I1 bearing acircumferential scale I8 indicating units of distance per unit of time,e. g., miles per hour. The dial Il is retained in adjusted angularposition by a small friction brake I9 comprisinga spring 20 secured tothe end wall of the rule body I by a fastener 2l and held tightlyagainst the periphery 22 of the dial I1 by a post 23. An index mark 24is formed on a projection 25 on the rule body l in such manner as tocooperate with the scale I8 t indicate the angular 'adjustment of thedial l1. Rotation, or angular adjustment, of the dial l1 causes thestrip 4 to be twisted or helically deformed, the pitch of such helicaldeformation depending upon the angular adjustment of said dial. y

A block 26 is slidably mounted in a guide slot 21 formed in the rulebody l and extending from the side wall thereof to the channel 3.Secured to the upper exposed surface of said block is a transparent cap28 which extends over and closely adjacent the upper surface of saidrule body l, as shown in Figs. 1 and 4, and which, in conjunction withthe block 26, constitutes a rider 35 slidable, or movablelongitudinally, over the rule body. An index mark 29 is placed on theedge of the cap 28 near the distance scale 2 for cooperation therewithto indicate the position of the rider 35 with respect to said scale. tosaid block 26, as by connecting studs 3|), 30 are tubular guide members3i, 3| which are slidable in the circular channel 3 and which preventWithdrawal of the slide block 26 from the guide slot. 21. The flexibleguide strip 4 passes through the tubular members 3| without contact. Adrum 32 constituting a time indicator and bearing on its periphery acylindrical scale 33 indicating units of time, e. g., hours and minutes,is rotatably held between the tubular guides 3l, 3|. The rule body hasin its upper face a slot 34 through which the scale 33 is visible, andthe transparent cap 28 of the rider 35 is provided with an index mark 36cooperating with said scale 33. The iiexible guide strip 4 passesthrough a slot 31 in the drum 32 so that, as the rider 35 is moved alongthe scale 2, the drum is rotated an amount determined jointly by theextent of such movement and the twist given the strip by the angularadjustment of the dial il.

The use of the device above described in conjunction with a suitablemap, whose scale correponds to the scale 2, is illustrated in Fig. 8.Assume that the aviator is leaving a starting point A to fly in thedirection of a station B. Before starting, his probable ground speed onthis initial course is computed or estimated and the dial I1 is turneduntil this estimated ground speed in miles per hour is indicated by theproper numeral at a point opposite the index mark 24. This movement ofthe dial is transmitted in reduced degree to the strip 4 by the gears I0and I4, so that the strip is given a slight, substantially uniform twistthroughout its length, Then the distance scale 2 is placed over the map,as shown in Fig. 8, and the rider 35 moved along said scale until theindex mark 29 is opposite the station B. As the rider 35 is moved, thetwist in the guide strip 4, resulting from the setting of the dial IT,turns the drum 32 and the scale 33, so that the time graduation on saidscale which is brought opposite the index mark 36 registers or indicatesto the pilot the time at which he would expect to reach, or be over,station B when flying at the assumed ground speed. Similarly, by movingthe rider to bring the index mark 29 opposite various intermediatepoints along the course, the expected time of arrival at these pointswill be registered by the indicator or scale 33, and, conversely, by sosetting the rider as to cause the indicator to register a given actualelapsed time (as shown by the pilots watch) the pilots position at thatSecured time will be indicated lon the map by the index mark 29 whetherthe ground is visible or not.

Assuming that the station B is a check station, or one whose identitycan be readily recognized from the air, when this station is reached theactual elapsed time of ilight (as shown by the pilots watch) is comparedwith the time reading given by the indicator 33 when the index mark 29is opposite this station. lf the times differ, then the actual elapsedtime can be used as the known factor and the ground speed the unknown.The rider 35 being left with its index mark 29 opposite the station B,the dial i1 is turned until the actual elapsed time is registered by thetime indicator 33. The speed scale i8 on the dial I1 then indicates thecorrect ground speed. As other check stations are reached, thereadjustment for ground speed can, in the same way, be rechecked andverified or corrected in accordance with conditions.

For convenience in accurately setting the guide strip 4 so that when theindex mark 29 on the rider 35 is at the zero point on the scale 2 thetime scale 35 on the drum 32 will also register zero, the end of saidstrip adjacent the zero end of the scale 2 may be secured, as by a pin5, to a hub 6 rotatably mounted in said rule body coaxial with thechannel 3, said hub having an operating handle 1.

I claim:

l. A pilotage instrument comprising, in combination, a rule body, anindicator comprising a scale graduated in units of time movable oversaid rule body, a twistable guide for said time scale, an adjustingmember movably mounted in said rule body and having a scale marked toindicate speed in units of distance per units cf time, and meansassociated with said adjusting member for twisting said guide.

2. A computing rule comprising, in combination, a rule body, a rotarytime indicator movable thereover, a dial adjustable in said rule bodyand marked to indicate speed in units of distance per units of time, anda twistable guide associated with saiddial for rotating said timeindicator, as it is moved over said rule body, to a variable extentdetermined by the adjusted position of said dial.

3. A pilotage instrument comprising, in combination, a rule body, arider slidably mounted on said body, a drum rotatably associated withsaid rider, a exible guide strip for said drum, said drum having aperipheral scale indicating units of time, a member adjustable in saidrule body and having a scale indicating speed in units of distance perunits of time, and means connecting said adjusting member and saidflexible strip adapted to twist said strip as said member is adjusted.

4. A pilotage instrument comprising, in combination, a rule body, arider slidably mounted on said body, a drum rotatably associated withsaid rider and having a peripheral time scale, a flexible strip on whichsaid drum is guided and adapted to iix the angular position thereof, arotatable dial having a speed scale, and means connecting said dial andsaid exible strip adapted to twist said strip as said dial is turned.

5. A pilotageinstrument comprising, in combination, a distance scale, atime indicator movable over said scale, a twistable guide for varyingthe indication of said time indicator as it is moved over said scale, amember adjustable in accordance with speed, and means associated withsaid member for twisting said guide.

l6. In a pilotage instrument, the combination of a rule body, a distancescale, a rotatable indicator having a scale marked in units of time,means for moving the indicator along the distance scale, a helicallydeformable guide for the indicator adapted to cause it to registervalues as it is moved over the scale which vary in accordance with thedistance moved and the pitch of the helical deformation of the guide, ascale marked toindicate speed in units of distance per units of time,selective means for choosing a particular speed on the speed scale, andmeans correlated therewith for adjusting the helical deformar tion ofthe guide.

7. An instrument for coordinating the three independently variable butmutually dependent factors of time, speed and distance including, incombination, a rule body, a linear distance scale, a drum bearing ascale graduated in units of a second factor, a slot formed inthe drum, aflexible guide for the drum adapted to pass through the slot, a scalegraduated in units of athird factor, a control member for the guideadapted to be adjusted in accordance with the third `factor, connectingmeans for transmitting the adjustment of the control member to theflexible guide,-

and means for moving the drum simultaneously along the distance scaleand the exible guide to cause it to indicate values which vary accordingto the distance moved and the adjustment of the guide.

8. In a pilotage instrument, the combination of a rule body, a guideslot extending longitudinally of the rule body, a distance scaleextending longitudinally of the rule body, a rider adapted to follow theguide slot, index means y carried by the rider adapted to cooperate Withthe distance scale, a rotatable indicator carried by th rider, ahelically deformable guide strip for the rotatable indicator, and amember for adjusting the pitch of the helical deformation of the guidemovably mounted in the rule body having a scale marked to indicate speedin units of distance per units of time.

/FRANKLIN A. REECE.

